This invention relates to integrated Schottky Barrier contact structures, and particularly to such integrated Schottky Barrier contact structures which are in integrated circuits utilizing dielectric isolation. The Schottky Barrier contact is a rectifying metal-semiconductor junction. Such Schottky Barrier contacts utilize the Schottky effect based upon the rectification characteristics exhibited by well known metal-semiconductor interfaces. Generally, the electrical characteristics of these contacts depend upon the work function of the metal as well as the electron affinity in the semiconductor material. The high frequency response of semiconductor contacts or diodes is well known and results because the conduction phenomena which occurs under forward bias is caused primarily by majority carriers falling from the semiconductor into the metal. Consequently, the frequency-limiting effect of minority carrier storage is minimized. This high frequency response makes the utilization of Schottky Barrier diodes in high frequency rectification power supplies, high speed logic in memory circuits, and other circuits such as microwave applications particularly desirable. However, such diodes have a very significant leakage current and a low breakdown voltage under reverse bias. Consequently, there has been a considerable effort in the integrated circuit art to improve such reverse characteristics. The soft breakdown of the conventional planar Schottky Barrier diodes formed in openings in dielectric insulating layers on semiconductor substrates has been found to be due to an "edge effect" occurring at the metal-semiconductor interface at the edges of the opening in the dielectric material. At such edges, high field concentrations give rise to excess leakage and low breakdown voltages. This edge effect is described in detail in the article "Silicon Schottky Barrier Diode With Near-Ideal I-V Characteristics", by M. P. Lepselter et al., The Bell System Technical Journal, February 1968, pp. 195-208. As this article indicates, guard ring structures have been proposed to relieve this "edge effect" and thereby improve the reverse current-voltage characteristics of the Schottky Barrier contact. Other approaches in dealing with this problem are discussed in the articles "Characteristics of Aluminum-Silicon Schottky Barrier Diodes", A. Y. C. Yu et al., Solid State Electronics, Volume 13, 1970, pp. 97-104, and "Planar Mesa Schottky Barrier Diodes", N. G. Anantha et al., IBM Journal of Research and Development, November 1971, pp. 442-445. A related approach to this problem of Schottky Barrier diodes is described in copending patent application, Ser. No. 305,636, filed Nov. 10, 1972, by Anantha et al., assigned to the assignee of the present application.
In addition, with the current trend in the integrated circuit art towards dielectric isolation in place of the currently standard junction isolation, there is a need for Schottky Barrier diode structures which would be readily integratable into such dielectrically isolated integrated circuits.